Transactions of the Royal Society of Tropical Medicine and Hygiene 106 (2012) 205–214 Contents lists available at SciVerse ScienceDirect Transactions of the Royal Society of Tropical Medicine and Hygiene j ourna l ho me pag e: htt p://www.elsevier.com/locate/trstmh Review Epidemiology of vitamin A deficiency and xerophthalmia in at-risk populations Justin C. Sherwin a,b,* , Mark H. Reacher a , William H. Dean c , Jeremiah Ngondi a a Department of Public Health and Primary Care, Institute of Public Health, University of Cambridge, UK b Centre for Eye Research Australia, Department of Ophthalmology, University of Melbourne, Australia c Nkhoma Eye Hospital, Malawi a r t i c l e i n f o Article history: Received 16 March 2011 Received in revised form 11 January 2012 Accepted 11 January 2012 Available online 11 February 2012 Keywords: Vitamin A Xerophthalmia Epidemiology Public health Nutrition Blindness a b s t r a c t Vitamin A deficiency (VAD) is an important public health problem worldwide that con- tributes significantly to the global burden of disease. Vitamin A deficiency disorders include xerophthalmia and increased risk of infectious diseases, both of which increase risk of mor- tality. Xerophthalmia is also a leading cause of preventable blindness. Areas with highly prevalent VAD often share common dietary and other environmental exposures, includ- ing poverty, infectious diseases, limited development and poor availability of vitamin A containing food. Globally, the prevalence of VAD has been declining, which may be due to widespread vitamin A supplementation in conjunction with measles immunisation in at-risk populations. Recent meta-analyses confirm that provision of vitamin A to children aged between 6 months and 5 years confers a significant mortality benefit. Further pre- ventative measures for VAD comprise improving availability of vitamin A containing food, including foods biofortified with vitamin A. Ensuring vitamin A is available in any form in adequate quantities remains problematic, especially in areas affected by environmen- tal catastrophes and conflict, and other areas where access to vitamin A containing foods and healthcare interventions is limited. Hence, it remains essential that maternal and child health workers remain vigilant for VAD in nutritionally vulnerable populations. © 2012 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved. 1. Introduction 1.1. Global burden of vitamin A deficiency In 2009, WHO global estimates indicated that 5.2 million preschool age children were affected with night blindness and that low serum retinol concentrations (<0.70 mol/l) affected 190 million preschool age children. 1 The latter estimate is equivalent to one-third of populations at risk of vitamin A deficiency (VAD). A further 7.8% of pregnant women in areas at risk have night blindness (9.75 million) * Corresponding author. Tel.: +44 1223 330 300; fax: +44 1223 330 349. E-mail address: justincsherwin@gmail.com (J.C. Sherwin). and 19.1 million have low retinol concentrations. 1 Num- bers affected with VAD are increasing since the WHO estimates were published in 1995, when it was estimated that approximately 3 million and 251 million preschool age children were affected with clinical VAD and biochemical VAD each year, respectively. 2 A separate global estimate published in 2002 estimated that there were approxi- mately 127 million preschool children with VAD (serum retinol <0.70 mol/l or displaying abnormal conjunctival impression cytology) and 4.4 million with xerophthalmia. 3 Vitamin A deficiency disorders (VADDs) reflect a heterogeneous grouping of health disorders that can be attributed in varying degrees to VAD. 3 Collectively, VADDs contribute significantly to the global burden of disease. 4 In 2004, it was estimated that, among children aged 0035-9203/$ – see front matter © 2012 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.trstmh.2012.01.004